imagesetinterpolation

Sets the interpolation method, setting an interpolation method affects the rendering of various functions in GD, such as the imagerotate() function.

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

The interpolation method, which can be one of the following:

• IMG_BELL: Bell filter.
• IMG_BESSEL: Bessel filter.
• IMG_BICUBIC: Bicubic interpolation.
• IMG_BICUBIC_FIXED: Fixed point implementation of the bicubic interpolation.
• IMG_BILINEAR_FIXED: Fixed point implementation of the bilinear interpolation (default (also on image creation)).
• IMG_BLACKMAN: Blackman window function.
• IMG_BOX: Box blur filter.
• IMG_BSPLINE: Spline interpolation.
• IMG_CATMULLROM: Cubic Hermite spline interpolation.
• IMG_GAUSSIAN: Gaussian function.
• IMG_GENERALIZED_CUBIC: Generalized cubic spline fractal interpolation.
• IMG_HERMITE: Hermite interpolation.
• IMG_HAMMING: Hamming filter.
• IMG_HANNING: Hanning filter.
• IMG_MITCHELL: Mitchell filter.
• IMG_POWER: Power interpolation.
• IMG_QUADRATIC: Inverse quadratic interpolation.
• IMG_SINC: Sinc function.
• IMG_NEAREST_NEIGHBOUR: Nearest neighbour interpolation.
• IMG_WEIGHTED4: Weighting filter.
• IMG_TRIANGLE: Triangle interpolation.

Returns TRUE on success or FALSE on failure.

<?php
// Load an image
$im = imagecreate(500, 500);

// By default interpolation is IMG_BILINEAR_FIXED, switch 
// to use the 'Mitchell' filter:
imagesetinterpolation($im, IMG_MITCHELL);

// Continue to work with $im ...
?>